Waste and toxic gas combustion reactor

ABSTRACT

A waste and toxic gas reactor for completely combusting produced gases with low NO x  emissions is provided. The reactor includes a plurality of staged air orifices that create a vortex in the combustion chamber. The vortex increases the residence time of the introduced gas molecules and thus facilitates complete combustion at lower temperatures.

BACKGROUND OF THE INVENTION

[0001] This invention relates to fuel burners such as are used in industrial furnaces. More particularly, the present invention relates to fuel reactors that may be used to burn produced waste and toxic gases in a controlled combustion process.

[0002] Perfect combustion of clean gases such as natural gas was achieved some time ago by the use of staged combustion reactors. One such staged combustion reactor is found in U.S. Pat. No. 4,708,637 entitled “Gaseous Fuel Reactor” to one of the current inventors, Cornel Dutescu.

[0003] Perfect combustion indicates that there are no toxic discharge products. While perfect combustion for clean gases has been shown, there are other non-clean produced gases that also have high heating values but are difficult to perfectly burn. Some of these other gases are produced from coal, others are products of solid waste gasification, and still others are the products of various chemical processes. Many of these other gases contain large hydrocarbon molecules and some of these other gases are contaminated with toxic elements (sometimes pure, sometimes in combinations) such as chlorine, fluorine, nitrogen, sulfur, or other potentially toxic substances. If burned imperfectly, these contaminated hydrocarbons are capable of producing dioxins and furanes which can be lethal even at very low concentrations.

[0004] In some parts of the world these produced gases become necessary fuel services to local industries and others because clean fuels are not readily available at an affordable price. However, it is desirable to burn these produced gases completely and safely. There is a perceived need for an apparatus capable of dissociating every molecule while also providing conditions conducive to full oxidation of the fuel elements. Full oxidation of the fuel elements will result in only the relatively harmless combustion products of CO₂ and H₂O.

[0005] In addition, with the constant influx of new environmental regulations requiring the effective control of combustion pollutants such as nitrogen oxidants (NO_(x)) which in turn produce photochemical oxidants, it is desirable to keep reaction temperatures low to reduce or eliminate NO_(x) formation. However, in most cases the low-temperature methods which have been developed cause inefficiencies and incomplete combustion.

[0006] The present invention is directed toward overcoming, or at least reducing the effects of, one or more of the problems set forth above.

SUMMARY OF THE INVENTION

[0007] In accordance with one aspect of the invention there is provided a reactor including an outer casing with first and second ends, an inner casing with first and second ends, an annulus formed between the outer and inner casings, and an air inlet assembly within the annulus comprising a plurality of non-radial orifices formed in the inner casing. The reactor also includes a reaction chamber with a centerline, a back plate enclosing the first end of the outer casing, and an orifice plate spaced from the back plate at the first end of the inner casing.

[0008] In some embodiments the reactor also includes tubular extensions attached to each of the plurality of non-radial orifices. The tubular extensions are located in the annulus between the inner and outer casings. In a preferred embodiment, the plurality of orifices are spaced equidistant from one another in a plurality of circular rows. Each one of the plurality of rows defines a combustion stage in the reaction chamber.

[0009] The reactor also includes a plurality of orifices in the orifice plate, each orifice having a centerline substantially parallel to the reaction chamber centerline. The orifice plate orifices may include extensions attached thereto.

[0010] In some embodiments the reactor includes a pilot burner extending through the back plate and the orifice plate into the reaction chamber.

[0011] In some embodiments the inner casing includes a first cylindrical portion, a second cylindrical portion of smaller diameter than the first cylindrical portion, and a conical portion connecting first and second cylindrical portions. The second cylindrical portion may include a plurality of small holes drilled therein. The conical portion and the second cylindrical portion constitute a discharge nozzle.

[0012] In some embodiments the annulus between the inner and outer casings is an air header and the space between the back plate and the orifice plate is a gas header.

[0013] In a preferred embodiment the non-radial air orifices create a vortex within the reaction chamber to increase the residence time of an introduced non-clean gas and facilitate perfect combustion of the non-clean gas at a low temperature. A centerline of each of the non-radial orifices creates a chord across the inner casing, and each of the chord-centerlines form an essentially equal, acute angle with a radius extending to each orifice.

[0014] In one embodiment there is disclosed a reactor including a plurality of concentric casings defining a plurality of concentric chambers including a combustion chamber; and an air distribution chamber surrounding the combustion chamber, the air distribution chamber including a plurality of orifices facilitating communication between the air distribution chamber and the combustion chamber. The plurality of orifices are formed in a wall of the combustion chamber in a non-radial manner. There is also a gas chamber adjacent to a first end of the combustion chamber, the gas chamber including at least one orifice facilitating communication between the gas chamber and the combustion chamber.

[0015] In some embodiments a tubular extension is attached to each of the plurality of gas chamber orifices. The centerline of the at least one orifice is substantially parallel to a centerline of the combustion chamber.

[0016] In some embodiments there may be tubular extensions attached to each of the plurality of non-radial orifices. The centerline of each the non-radial orifices creates a chord across the inner casing, with each of the centerlines forming an equal, acute angle with a radius extending to each orifice. The plurality of orifices are spaced equidistant from one another in a plurality of circular rows, with each row defining a combustion stage in the reaction chamber.

[0017] In some embodiments a pilot burner extends into the reaction chamber.

[0018] The air chamber includes an inner casing and an outer casing, each with first and second ends, wherein the diameters of the first ends of each casing are larger than the diameters of the second ends.

[0019] There is also described a method of combusting waste or toxic gases. The steps include introducing a waste or toxic gas into a reaction chamber, introducing an oxygen containing gas into the reaction chamber, creating a vortex within the reaction chamber, and completely combusting the waste or toxic gas with the oxygen-containing gas in the reaction chamber.

[0020] In one version of the method the step of introducing a waste or toxic gas into a reaction chamber further includes the introduction of the waste or toxic gas into the reaction chamber along centerlines parallel to a reaction chamber centerline.

[0021] The combustion method may also include the steps of introducing the oxygen-containing gas into the reaction chamber transverse to the reaction chamber centerline, and the combustion method may be a staged combustion.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The foregoing and other features and aspects of the invention will become further apparent upon reading the following detailed description and upon reference to the drawings in which:

[0023]FIG. 1 is a cross-sectional perspective view of the reactor in accordance with the present invention.

[0024]FIG. 2 is a cross-sectional perspective view of a portion of the embodiment according to FIG. 1.

[0025]FIG. 3 is a diagrammatical front view of the portion the reactor according to FIG. 1.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0026] Illustrative embodiments of the invention are described below. In the interest of clarity, not all features of an actual implementation are described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, that will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.

[0027] Turning now to the Figures, and in particular FIGS. 1-2, one embodiment of reactor 2 in accordance with the present invention is shown. Reactor 2 includes an outer casing 4 and an inner casing 6. Outer casing 4 and inner casing 6 are substantially concentric. In the preferred embodiment shown, outer casing 4 and inner casing 6 have approximately the same shapes along the length of each, but in alternative embodiments the shapes of each may sometimes be somewhat different. Outer casing 4 includes a first substantially cylindrical portion 8, a second substantially cylindrical portion 10 having a smaller diameter than first cylindrical portion 8, and a conical portion 12 connecting first and second cylindrical portions 8 and 10. In the alternative, outer casing 4 has no change in cylindrical diameter and therefore has no conical portion. Inner casing 6 similarly includes a first substantially cylindrical portion 14, a second substantially cylindrical portion 16 having a smaller diameter than first cylindrical portion 14, and a conical portion 18 connecting first and second cylindrical portions 14 and 16. The first cylindrical portion 14 of inner casing 6 defines a reaction chamber, for example combustion chamber 30 with centerline 31. The annulus created between outer casing 4 and inner casing 6 defines an oxygen-containing chamber, for example air header 32. Conical portion 18 and second cylindrical portion 16 define a discharge nozzle 34 through which combusted products exit. Second cylindrical portion 16 may include a plurality of small holes 36 drilled therein to facilitate fluid communication between air header 32 and discharge nozzle 34.

[0028] A first end 20 of outer casing 4 is closed by a back plate 22, while a first end 24 of inner casing 6 is closed by an orifice plate 26 spaced from back plate 22. Orifice plate 26 also extends to the inner surface of outer casing 4. Each of back plate 22 and orifice plate 26 have a central aperture through which a clean gas pilot 28 extends. Clean gas pilot 28 may be any clean gas burner, such as the clean gas burner described in U.S. Pat. No. 4,708,637 which is herein incorporated by reference. A generally cylindrical gas header 38 is created in the space between back plate 22 and orifice plate 26. Gas header 38 contains the combustion gases that may be waste gases, toxic gases, or other produced non-clean gases. An inlet 39 in first end 20 of outer casing 4 provides gas to gas header 38.

[0029] Orifice plate 26 includes a plurality of equally-spaced orifices 40 arranged in a generally circular pattern around the plate. Each of orifices 40 has a centerline 42 that is substantially parallel with combustion chamber centerline 31. Each of orifices 40 may also include an orifice extension tube (not shown) concentrically attached to each of orifices 40 on the gas header 38 side of the orifice plate. Orifices 40 comprise the gas inlet into combustion chamber 30.

[0030] Air header 32, which is created by the annulus between outer casing 4 and inner casing 6, is supplied an oxygen-containing gas such as air through a flanged nozzle 46, which facilitates fluid communication between an air source (not shown) and air header 32. An air inlet assembly 48 facilitates the introduction of the air into combustion chamber 30. Air inlet assembly 48 includes a plurality of non-radial orifices 50, each with a concentrically attached orifice extension tube 52. Orifice extension tubes 52 store radiant heat from combustion chamber 30 during the reaction and transfer the heat to the incoming combustion air. Together with outside surface 80 of combustion chamber 30, orifice extension tubes 52 form a studded heat transfer tube. In an alternative embodiment, there are no orifice extension tubes attached to orifices 50. Non-radial orifices 50 are arranged in four circular rows 54, 56, 58, and 60 in the embodiment shown, but any number of rows may be substituted for a particular application. Each row represents a stage in the combustion process. The plurality of stages advantageously allows for cooler combustion temperatures while also completely burning the produced gases. Non-radial orifices 50 are substantially equally spaced around combustion chamber 30. Non-radial orifices 50 and their associated extension tubes 52 are arranged such that the centerlines of each, for example centerline 62 seen in FIG. 3, do not converge to the center of combustion chamber 30 but instead form geometric chords, such as chords 64. The centerline chords 64 of each of orifices 50 form essentially equal, acute angles 66 with a planar radius 68 extending from centerline 31 of combustion chamber 30 to each orifice. FIG. 3 illustrates the angles 66 herein described. The direction of centerline chords 64 force the combustion air streams into generally circular patterns around centerline 31 of combustion chamber 30.

[0031] Returning to FIG. 1, each of non-radial orifices 50 allows a stream of air to enter combustion chamber 30, which it does as a vector, such as air vectors 70. Each of gas orifices 40 permits a stream of gas to enter combustion chamber 30, which also enters as a vector, such as gas vectors 72. Gas vectors 72 are substantially parallel with combustion chamber centerline 31, while air vectors 70 are transverse to combustion chamber centerline 31. Air vectors 70 impinge on gas vectors 72 (i.e. the centerlines 62 of the air orifices 50 intersect the centerlines 42 of gas orifices 40) to form a resultant vector that follows a generally spiral path and thus creates a vortex. The spiral path taken by the gas molecules advantageously increases the residence time of the gases and facilitates perfect combustion of waste, toxic, and other produced gases. The combustion takes place in stages, for example the four stages shown in the embodiment shown, which allows for lower temperatures and an associated decrease in NO_(x) formation.

[0032] Clean gas pilot 28 provides combustion chamber 30 with the sufficient ignition temperature to begin the dissociation of the produced gases. The pilot gas may be natural gas, propane, or other clean gases. The collisions between produced (non-clean) gas molecules and air molecules (as air vectors 70 impinge on gas vector 72) further enhances the dissociation of the gas. The new molecules (products of combustion) and dissociated atoms travel a spiral course toward exit discharge nozzle 34. With the impingement of air vectors 70 on gas vectors 72, there is a much greater probability that the fuel atoms will meet oxygen atoms and completely combust the produced gas without any toxic discharge and very little if any NO_(x).

[0033] Discharge nozzle 34 and the exiting gasses are cooled by small air streams discharging through the plurality of small holes 36 drilled all along the second cylindrical portion 16 of inner casing 6. Reactor 2 defines an isentropic system, and with ambient combustion air, typically outer casing 4 will advantageously be at room temperature.

[0034] It is contemplated that injection pressures for both produced gases and combustion air will be low, however isentropic combustion chamber 30 generates enough pressure when the reactants combust to ensure high jet speeds if back pressure is low. High jet speeds are fluid velocities of over two-hundred feet per second. High jet speeds advantageously provide high convection heat transfer rates as the convection coefficient is an exponential function of the gas speed available at the heat transfer surface. When back pressure is near atmospheric, the jet speed exceeds five-hundred feet per second.

[0035] As can be seen from the foregoing, the present invention provides a novel waste or toxic gas reactor which maintains a low flame temperature to avoid the formation of pollutants while achieving complete combustion through the use of multiple stage combustion and vortex-action. The invention provides for the use of a clean gas to promote the combustion of the waste gases.

[0036] While the present invention has been described with reference to the specific embodiments, it will be appreciated that the invention may be embodied in other specific forms without departing from its spirit and scope. For example, with some variations, reactor 2 can be adapted to bum liquid or sold fuels. Accordingly, the described embodiment is to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. 

What is claimed is:
 1. A reactor comprising: an outer casing with first and second ends; an inner casing with first and second ends, said inner casing forming a reaction chamber with a centerline; an annulus formed between the outer and inner casings; an air inlet assembly within the annulus comprising a plurality of non-radial orifices formed in the inner casing; a back plate enclosing the first end of the outer casing; an orifice plate spaced from the back plate at the first end of the inner casing; and a gas header being formed within the outer casing between the back plate and the orifice plate.
 2. The reactor of claim 1 further comprising tubular extensions attached to each of the plurality of non-radial orifices.
 3. The reactor of claim 2 wherein the tubular extensions are located in the annulus between the inner and outer casings.
 4. The reactor of claim 1 wherein the plurality of orifices are spaced equidistant from one another in a plurality of circular rows.
 5. The reactor of claim 1 further comprising a plurality of orifices in the orifice plate, each orifice having a centerline substantially parallel to the reaction chamber centerline.
 6. The reactor of claim 5 further comprising a tubular extension attached to each of the plurality of orifices.
 7. The reactor of claim 1 further comprising a pilot burner extending through the back plate and the orifice plate into the reaction chamber.
 8. The reactor of claim 1 wherein the inner casing further comprises a first cylindrical portion, a second cylindrical portion of smaller diameter than the first cylindrical portion, and a conical portion connecting first and second cylindrical portions.
 9. The reactor of claim 8 further comprising a plurality of small holes in the second cylindrical portion.
 10. The reactor of claim 1 wherein a centerline of each of the non-radial orifices creates a chord across the inner casing forming an acute angle with a radius extending to each orifice.
 11. The reactor of claim 5 wherein the centerlines of the orifices in the orifice plate intersect chords formed by the centerlines of the non-radial orifices.
 12. The reactor of claim 5 wherein the centerlines of the non-radial orifices are perpendicular to the centerlines of the orifices in the orifice plate.
 13. A combustion reactor comprising: an outer casing with first and second ends; a back plate enclosing the first end of the outer casing; an inner casing with first and second ends, said inner casing forming a reaction chamber with a centerline; an orifice plate spaced from the back plate and connected to the first end of the inner casing, said plate having a plurality of orifices; an annulus formed between the inner and outer casings; an air inlet assembly comprising a plurality of non-radial orifices formed in the inner casing; a gas header being formed within the outer casing between the back plate and the orifice plate; wherein the centerlines of the orifices in the orifice plate intersect chords formed by the centerlines of the non-radial orifices.
 14. The reactor of claim 13 further comprising tubular extensions attached to each of the non-radial orifices within the annulus formed between the inner and outer casings.
 15. The reactor of claim 13 further comprising a pilot burner extending through the back plate and the orifice plate into the reaction chamber.
 16. A method of combusting waste or toxic gases comprising the steps of: introducing a waste or toxic gas into a reaction chamber through orifices having centerlines parallel to the centerline of the reaction chamber; introducing an oxygen containing gas into the reaction chamber through a plurality of non-radial orifices formed in the walls of the reaction chamber, the chords of said non-radial orifices forming chords in the reaction chamber that form an acute angle with a radius of the reaction chamber; creating a vortex within the reaction chamber; and completely combusting the waste or toxic gas with the oxygen-containing gas in the reaction chamber.
 17. The method of claim 16 wherein the step of completely combusting the waste or toxic gas further comprises staged combustion created by a plurality of rows of non-radial orifices. 